We compute the isobaric vapour-liquid diagram of two binary mixtures at 760 mmHg. The mixtures are acetone-water and acetone-methanol. Liquid phase activity coefficients are computed using the NRTL model proposed by Renon and Prausnitz in 1968. Model parameters are taken from Distil by Hyprotech Ltd. We use NMinimize to obtain the bubble temperature at various liquid phase compositions. It is also possible to use FindRoot to perform the same computation. We also plot the excess enthalpy and excess Gibbs free energy versus composition at 298.15K.